Digital projectors, such as digital mirror devices (DMD) and liquid crystal display (LCD) projectors, project high quality images onto a viewing surface. Both DMD and LCD projectors utilize high intensity lamps and reflectors to generate the light needed for projection. Light generated by the lamp is concentrated as a ‘fireball’ that is located at a focal point of a reflector. Light produced by the fireball is directed into a projection assembly that produces images and utilizes the generated light to form the image. The image is then projected onto a viewing surface. Misalignment of the focal point causes degradation of the image since less light is captured and creates ‘hot spots’ on the screen instead of a uniform brightness.
Efforts have been directed at making projectors more compact while making the image of higher and higher quality. As a result, the lamps utilized have become more compact and of higher intensity. Higher intensity lamps produce high, even extreme heat. The outer surface of the lamps can approach temperatures of 900° C. As a result, projector designs must account for the intense heat.
In addition, contaminants such as oils or other contaminants, reduce the useful life of a lamp assembly if they are allowed to be deposited on the lamp. Such contamination of the lamp can occur if a user handles or touches the bulb portion of the lamp. The natural oils from the user's hands may be deposited on the lamp. Additionally, if there is any dirt or other contaminants on the user's hands, the dirt or other contaminants may also get deposited on the lamp. When the lamp is repeatedly heated to an operating temperature, such contamination on the lamp may reduce the operating life of the lamp or, in some cases, may cause the lamp to break and potentially damage surrounding structures.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.